I am looking for info as to a 3 or 5 turm Magnetic loop.(using 1.0"
hardline for outdoor stabilty) along with the usual tuning cap. Will
it produce any better results when campared to the same diameter mag
loop but just 1 turn. Will I get deeper nulls/improved directivity?
This is meant to be a rcv. loop only. I want to use large dia.
hardline due to its built in solid outer metal conductor. I figure It
will be easier to stabilize the turns. Which brings me to another
question. I realize turn counts Vs spacing is a consideration with
wire loops. But what are the implications with a multi turn coax
loop. Should the hardline turns be basiclly intimate with the black
plastic outer conductor touching or should the turns be seperated
by "X" I would think that there should be some sort of spacing. Any
guidance for those who have this info or links to find same would be
greatly appreciated.

John,

That makes sense. At MW especially the additional capacitance could
be problematical. At lower frequencies it might actually prove
beneficial to some degree.

73,

'Bear' NH7SR

--- In loopantennas@..., john nelson <jnelson123_us@y...>
wrote:

I was treating the telephone wire as if it was one
cable. Since I was establishing the correct length of
wire by trial and error it was easier that way. I
also theorized that the four wires were so close
together that there would be a stray capacitance
problem if I actually used them as separate windings.

John N.
--- Michael Hebert <qrpbear@y...> wrote:

John,

Very impressive looking antenna. One question...

Why did you connect the 4-conductor cable wires in
parallel? I assume
to resonate the loop.

I am thinking of something similar but series
connected and untuned.

73,

'Bear' NH7SR

I was treating the telephone wire as if it was one
cable. Since I was establishing the correct length of
wire by trial and error it was easier that way. I
also theorized that the four wires were so close
together that there would be a stray capacitance
problem if I actually used them as separate windings.

John N.
--- Michael Hebert <qrpbear@...> wrote:

John,

Very impressive looking antenna. One question...

Why did you connect the 4-conductor cable wires in
parallel? I assume
to resonate the loop.

I am thinking of something similar but series
connected and untuned.

73,

'Bear' NH7SR

--- In loopantennas@..., "John Nelson"
<jnelson123_us@y...> wrote:

I just posted a picture of my long wave and middle

wave loop in the

pictures section. The actual antenna was made

entirely of salvaged

materials for the exception of the brass bolts and

nuts in the
center

section. The outer loop is made of 4 wire flat

telephone cable
with

all sections paralleled. This section is a spiral

loop on just one

side of the support sections. The next section is

the MW loop and
is

made of 14 ga. conduit wire and is wound in a

basket fashion so as
to

hold down capacitance. The coupling loop is on

the inside and is
two

turns of two conductors in parallel. I thought

originally that I

could use the same loop for both bands using taps

but the
capacitance

of the wire made tuing up high enough for MW

impossible. Using

Varicap diodes in series it is possible to tune

_nearly_ all the

bands but not all. I finally put in a switch to

switch one pair of

diodes in and out and can easily cover more than

half of each band

with the high or low setting. The metal box

contains a FET

preamplifier, in/out switches, and the voltage for

the diodes. It

certainly is easier to tune the diodes remotely

than to bend over
and

adjust a variable cap. BTW the support section is

not near strong

enough-that wire in the LW section is really

heavy. On the 175-525

KHZ band, I have yet to detect anything but

non-directional beacons

but I'm still looking.

_______________________________
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开云体育

Michael,

Hey! It's finished! I am really looking forward to seeing the
pictures. Did you use the remote volume control motor for tuning?

73,

'Bear' NH7SR

--- In loopantennas@..., "Michael Stevenson"
<portstevos@t...> wrote:

My new magnetic loop antenna for shortwave is now fully finished

and in use. It's performance is extremely impressive and out performs
my 15 and 17 metre longwires. This is an active loop with a pre-amp
and tunes from below 2.3 MHz all the way up to 17.9 MHz, all with
full remote control.

I will be posting full details and photos to this group in the next

few days with a review of it's performance.

Best regards!

Michael Stevenson,
Australia.

John,

Very impressive looking antenna. One question...

Why did you connect the 4-conductor cable wires in parallel? I assume
to resonate the loop.

I am thinking of something similar but series connected and untuned.

73,

'Bear' NH7SR

--- In loopantennas@..., "John Nelson"
<jnelson123_us@y...> wrote:

I just posted a picture of my long wave and middle wave loop in the
pictures section. The actual antenna was made entirely of salvaged
materials for the exception of the brass bolts and nuts in the

center

section. The outer loop is made of 4 wire flat telephone cable

with

all sections paralleled. This section is a spiral loop on just one
side of the support sections. The next section is the MW loop and

is

made of 14 ga. conduit wire and is wound in a basket fashion so as

to

hold down capacitance. The coupling loop is on the inside and is

two

turns of two conductors in parallel. I thought originally that I
could use the same loop for both bands using taps but the

capacitance

of the wire made tuing up high enough for MW impossible. Using
Varicap diodes in series it is possible to tune _nearly_ all the
bands but not all. I finally put in a switch to switch one pair of
diodes in and out and can easily cover more than half of each band
with the high or low setting. The metal box contains a FET
preamplifier, in/out switches, and the voltage for the diodes. It
certainly is easier to tune the diodes remotely than to bend over

and

adjust a variable cap. BTW the support section is not near strong
enough-that wire in the LW section is really heavy. On the 175-525
KHZ band, I have yet to detect anything but non-directional beacons
but I'm still looking.

开云体育

I just posted a picture of my long wave and middle wave loop in the
pictures section. The actual antenna was made entirely of salvaged
materials for the exception of the brass bolts and nuts in the center
section. The outer loop is made of 4 wire flat telephone cable with
all sections paralleled. This section is a spiral loop on just one
side of the support sections. The next section is the MW loop and is
made of 14 ga. conduit wire and is wound in a basket fashion so as to
hold down capacitance. The coupling loop is on the inside and is two
turns of two conductors in parallel. I thought originally that I
could use the same loop for both bands using taps but the capacitance
of the wire made tuing up high enough for MW impossible. Using
Varicap diodes in series it is possible to tune _nearly_ all the
bands but not all. I finally put in a switch to switch one pair of
diodes in and out and can easily cover more than half of each band
with the high or low setting. The metal box contains a FET
preamplifier, in/out switches, and the voltage for the diodes. It
certainly is easier to tune the diodes remotely than to bend over and
adjust a variable cap. BTW the support section is not near strong
enough-that wire in the LW section is really heavy. On the 175-525
KHZ band, I have yet to detect anything but non-directional beacons
but I'm still looking.

At 11:59 PM 8/10/04 -0700, you wrote:

Installation of DSL has caused terrible overnight
buzzing from the 500's to about 1000kHz.

Phone company made adjustments at street and
house.

Buzzing on portable radios re-radiated in vicinity?????????????

Hi:

I'm sorry I am no help re your problem... but I will be reading the mail as I am curious about your EMI situation and the DSL installation.? Does your phone line come to your house via buried cable or is an overhead line from the pole?? I have a DSL installation at this location .... in fact the outlet for the DSL modem and the modem itself are located about 1 1/2 ft from my operating position ..... I experience no noise from it what so ever .... however, I will check a little more closely on the frequencies you mention.? By the way the phone line here comes in via a buried cable (6 pairs) the local telephone company installed about 3 or 4 years ago.

Now I did have some noise problem from the telephone installation about 2 years ago.? The distribution within the house comes from the power panel.? That is they terminate the lines from outside and distribute lines within the house from that location.? At one point I had 4 lines terminated from outside and 5 cables going off to different locations within the house.? Over the years it became a rats nest of connections and wires.? Even when the phone company installed the new underground cable from the lane the rats nest remained.? Finally I couldn't stand it any more and I found a couple of 24 place barrier strips in the junk box and I mounted them on the wood backing of the power panel.? I then methodically terminated the incoming lines and the internal lines to the barrier strips.? I then drew up a schematic with the termination numbers.? I then cross connected the terminals to effect the desired distribution.? I used a 'LED' test tool to make sure the polarity of every line showed 'green' at every telephone jack.? Magically the noise stopped and the terminations really looked professional.? When they came to install the DSL service the installer was amazed at the setup .... 'this can't be our work' , he said!

Jim Dunstan
Thunder Bay, ON

Installation of DSL has caused terrible overnight
buzzing from the 500's to about 1000kHz.

Phone company made adjustments at street and
house.

Buzzing on portable radios re-radiated in
vicinity
of the four phones in the house.

On the outdoor phone line, portable radio reveals
that buzzing is propagated parallel to phone
line, not perpendicular.

Buzzing the loudest near our strongest overnight
signal at this location, 710kHz (710 KIRO/Seattle
50kW U2).

Why the buzzing only occurs overnight I haven't
figured out.

During the day = a hissing or whining sign on
weaker 1kW frequencies, even higher up the dial
(e.g. 1400kHz).

The old radio shack terk clone does not even help
that much at night.

Any info on what to tell phone company to do
would be very much appreciated, thanks...tom:

=====
Tom, webmaster, indigotalkradio
www.geocities.com/indigotalkradio



__________________________________
Do you Yahoo!?
New and Improved Yahoo! Mail - Send 10MB messages!

It probably means the loop is not really tuned to null; instead it
is tuned -near- null, and is putting out just enough at 180 out of
phase with the internal ferrite to cancel out the signal being
received by it directly.

Steve Greenfield

--- realrussian <realrussian@...> wrote:

At 07:28 PM 8/10/04 +0000, you wrote:

Thanks, but what about my question regarding "auto disconnect" of the
internal ferrite bar?? When I turn the loop to null a strong, local
station (I don't hear ANYTHING)doesn't that suggest that the internal
antenna has been defeated in some way?

I am sure there is no 'auto disconnect' .... most receivers with the ferrite antenna that have external antenna connections will operate both at the same time.? There are a few exceptions .... for example the Sony 7600GR will disconnect the AM antenna when an external antenna jack is plugged in.? The disconnect is mechanical however.? A similar Grundig radio ... the YB400 with the same type antenna jack only disconnects the whip on SW .... but leaves the internal AM antenna.?

However that does not explain the strange behaviour you are experiencing.

Jim Dunstan
Thunder Bay, ON

According to Terks website, and product brochure, the Terk AM
Advantage antenna is "omnidirectional". Is that true? I thought

all

loop antennas were very directional. It IS a loop isn't it? It
looks like a loop, it's a big circle.

The Terk brochure is in error.

According to Terks website, and product brochure, the Terk AM
Advantage antenna is "omnidirectional". Is that true? I thought

all

loop antennas were very directional. It IS a loop isn't it? It
looks like a loop, it's a big circle.

According to Terks website, and product brochure, the Terk AM
Advantage antenna is "omnidirectional". Is that true? I thought all
loop antennas were very directional. It IS a loop isn't it? It
looks like a loop, it's a big circle.

Thanks, but what about my question regarding "auto disconnect" of the
internal ferrite bar? When I turn the loop to null a strong, local
station (I don't hear ANYTHING)doesn't that suggest that the internal
antenna has been defeated in some way?

--- In loopantennas@..., Jim Dunstan <jimdunstan@r...>
wrote:

At 10:38 PM 8/9/04 +0000, you wrote:

OK, I hooked the loop (a cheap, simple little plastic thing that
comes with an am/fm hifi receiver for the am part) up 1 wire to "am
antenna" and 1 wire to "ground". I tuned to a strong local

station.

When I rotated the loop for strong signal it sounded about like the
internal ferrite bar. But, when I rotated to null the station

signal

I got nothing. Does this indicate that something automatically
disconnects the internal ferrite bar when I have the loop hooked
up?

Okay .... I thought you were using a tuned loop. The loop you

describe

will be an inferior antenna to your built in ferrite rod antenna.

It is

designed for receivers with relatively high gain and no internal

antenna

(HiFi receiver). It will work fine for the purpose of picking up

strong

local signals. A tuned loop is another thing all together. They

have

multi turns and are tuned with a capacitor so they come to

resonance. When

the do come to resonance they create a strong electromagnetic field

at a

very narrow frequency bandwidth. This field can then be coupled to

your

receiver by either bringing a receiver with a ferrite rod antenna

into its

vicinity or if doesn't have a built in antenna you couple using a

wire turn

or two as a link. The loop you have would make an excellent link

to a

tuned loop antenna. It is in fact exactly what I use for my Hi Fi

set.

My set has the same small plastic loop (8 1/2" dia es 3 turns) I

use it to

couple to my tuned loop. The Hi Fi set works just fine with the

plastic

loop when receiving local AM stations. However if I want to pick

up

stations in say Duluth (about 160 miles away) I bring the plastic

loop

close to my tuned loop, which I tune to the same frequency. The

difference

in reception is like night and day. The signal increases at least

20 to 30 DB.

Jim Dunstan
Thunder Bay, ON

At 10:38 PM 8/9/04 +0000, you wrote:

OK, I hooked the loop (a cheap, simple little plastic thing that
comes with an am/fm hifi receiver for the am part) up 1 wire to "am
antenna" and 1 wire to "ground".? I tuned to a strong local station.?
When I rotated the loop for strong signal it sounded about like the
internal ferrite bar.? But, when I rotated to null the station signal
I got nothing.? Does this indicate that something automatically
disconnects the internal ferrite bar when I have the loop hooked up?????????????

Okay .... I thought you were using a tuned loop.? The loop you describe will be an inferior antenna to your built in ferrite rod antenna.? It is designed for receivers with relatively high gain and no internal antenna (HiFi receiver).? It will work fine for the purpose of picking up strong local signals.? A tuned loop is another thing all together.? They have multi turns and are tuned with a capacitor so they come to resonance.? When the do come to resonance they create a strong electromagnetic field at a very narrow frequency bandwidth.? This field can then be coupled to your receiver by either bringing a receiver with a ferrite rod antenna into its vicinity or if doesn't have a built in antenna you couple using a wire turn or two as a link.? The loop you have would make an excellent link to a tuned loop antenna.? It is in fact exactly what I use for my Hi Fi set.

My set has the same small plastic loop (8 1/2" dia es 3 turns)? I use it to couple to my tuned loop.? The Hi Fi set works just fine with the plastic loop when receiving local AM stations.? However if I want to pick up stations in say Duluth (about 160 miles away) I bring the plastic loop close to my tuned loop, which I tune to the same frequency.? The difference in reception is like night and day.? The signal increases at least 20 to 30 DB.

Jim Dunstan
Thunder Bay, ON

At 09:51 AM 8/8/2004, you wrote:

I have been looking for a decent medium-wave AM loop antenna. I have
found a Terk AM-1000 AM Advantage Antenna for $31.70 plus shipping. My
questions are:

1) Can I find a better antenna than the Terk AM-1000 for about $30?

Probably not unless you are willing to build it. If that is the
case you could likely build a much better antenna but it will be
larger.

2) Can I find a better price on the Terk AM-1000?

I did a Froogle search and best price was $29.99



If you want a commercial product this may well be the best deal
on a price/performance basis!

73

Phil

-------------------------------------------------------------------------
Phil Lefever KB?NES Twin Cities Repeater Club
kb0nes@... Burnsville,MN

OK, I hooked the loop (a cheap, simple little plastic thing that
comes with an am/fm hifi receiver for the am part) up 1 wire to "am
antenna" and 1 wire to "ground". I tuned to a strong local station.
When I rotated the loop for strong signal it sounded about like the
internal ferrite bar. But, when I rotated to null the station signal
I got nothing. Does this indicate that something automatically
disconnects the internal ferrite bar when I have the loop hooked up?


--- In loopantennas@..., Jim Dunstan <jimdunstan@r...>
wrote:

At 04:01 PM 8/7/04 +0000, you wrote:

I just bought a Sangean PRD-2 radio. It works great on the

internal

AM antenna. Just for experimentation, I want to hook up an

external

loop antenna. It has 2 terminals on the back. One marked "am
antenna" and the one next to it marked "ground". My question is,
where do the 2 wire leads from the antenna go? I assume the ground
is for a ground wire and not the antenna. Do the 2 wire leads from
the antenna both go to the terminal marked "am
antenna"? What?

The radio more than likely uses a ferrite rod antenna/front end
inductor. If it has a terminal for the AM receiver it will in all

likely

hood be connected to a wire link wound around the ferrite rod. In

this

case you have 2 choices for coupling to a tuned loop.

1. Simply ignore the connectors and making a physical connection

between

the loop and the radio. Tune the radio to the frequency of your

choice,

then tune the loop to the same frequency and orient the loop and

radio for

best reception.

2. If your loop has a pair of wires coming out (usually from a

coupling

link) then simply connect one wire to the 'AM Antenna' connector

and the

other to the one marked 'ground'. If the wire from the loop is a

coax type

wire, then connect the centre conductor to the 'AM Antenna'

connector and

the shield to the 'Ground' connector.

Experiment with both methods.

Jim Dunstan
Thunder Bay, ON

1) Can I find a better antenna than the Terk AM-1000 for about $30?

Find no. Build yes.

2) Can I find a better price on the Terk AM-1000?

Probably not. What is your source? I had assumed the model was
discontinued.